package analysis.syntaxtree;import analysis.visitors.TypeVisitor;import analysis.visitors.Visitor;public class BooleanType implements Type {  private static BooleanType instance = new BooleanType();  public static BooleanType instance() {    return instance;  }  private BooleanType() { }  public void accept(Visitor v) {    v.visit(this);  }  public Type accept(TypeVisitor v) {    return v.visit(this);  }  @Override  public String toString() {    return "boolean";  }}